Serum prealbumin and albumin are excellent markers for nutritional status. Their serum levels could be influenced by several clinical situations that can mask their response as nutritional markers. This study was done including 100 patients admitted with different acute emergency illnesses in order to determine and quantify their serum levels of albumin and prealbumin in medical emergency and to determine if the clinically significant changes in the serum albumin level can be reliably predicted by earlier changes in the serum prealbumin; a marker which is more specific in situations of greater nutritional risk. The results of this study showed a significant reduction of the serum prealbumin levels in every group of emergency medical admission, with the exception of the renal medical emergency group that showed a minimal reduction of the serum prealbumin level, and a non- significant difference in relation to the control group.